Re: [patch 6/8] x86/entry: Move irq tracing to syscall_slow_exit_work

Alexandre Chartre
2020-02-27T16:13:07Z

On 2/25/20 11:08 PM, Thomas Gleixner wrote:
> which removes the ASM IRQ tracepoints.

This moves irq tracing to syscall_return_slowpath, not syscall_slow_exit_work,
right?

alex.

> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> arch/x86/entry/common.c | 2 ++
> arch/x86/entry/entry_32.S | 3 ++-
> arch/x86/entry/entry_64.S | 3 ---
> 3 files changed, 4 insertions(+), 4 deletions(-)
>
> --- a/arch/x86/entry/common.c
> +++ b/arch/x86/entry/common.c
> @@ -299,6 +299,8 @@ static void syscall_slow_exit_work(struc
>
> local_irq_disable();
> __prepare_exit_to_usermode(regs);
> + /* Return to user space enables interrupts */
> + trace_hardirqs_on();
> }
> NOKPROBE_SYMBOL(syscall_return_slowpath);
>
> --- a/arch/x86/entry/entry_32.S
> +++ b/arch/x86/entry/entry_32.S
> @@ -812,7 +812,7 @@ SYM_CODE_START(ret_from_fork)
> movl %esp, %eax
> call syscall_return_slowpath
> STACKLEAK_ERASE
> - jmp restore_all
> + jmp restore_all_switch_stack
>
> /* kernel thread */
> 1: movl %edi, %eax
> @@ -1077,6 +1077,7 @@ SYM_FUNC_START(entry_INT80_32)
>
> restore_all:
> TRACE_IRQS_IRET
> +restore_all_switch_stack:
> SWITCH_TO_ENTRY_STACK
> CHECK_AND_APPLY_ESPFIX
> .Lrestore_nocheck:
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -172,8 +172,6 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_h
> movq %rsp, %rsi
> call do_syscall_64 /* returns with IRQs disabled */
>
> - TRACE_IRQS_ON /* return enables interrupts */
> -
> /*
> * Try to use SYSRET instead of IRET if we're returning to
> * a completely clean 64-bit userspace context. If we're not,
> @@ -340,7 +338,6 @@ SYM_CODE_START(ret_from_fork)
> UNWIND_HINT_REGS
> movq %rsp, %rdi
> call syscall_return_slowpath /* returns with IRQs disabled */
> - TRACE_IRQS_ON /* user mode is traced as IRQS on */
> jmp swapgs_restore_regs_and_return_to_usermode
>
> 1:
>